1. Field of the Invention
The present invention relates to a method of transferring an image obtained on an image transfer sheet to other image-receiving members such as cloth, canvas, Japanese paper, bond paper, wood, leather, glass, earthenware and metal, without impairing the feeling and texture of each of the above-mentioned image-receiving members. In this case, the image formed on the image transfer sheet is obtained using the following image forming apparatuses:
1) an electrophotographic copying apparatus capable of producing a toner image by the xerography comprising an electrostatic image transfer step, PA1 2) a printer capable of transferring a thermofusible ink or sublimation-type dye by the thermal image transfer recording method, PA1 3) an ink-jet printer capable of transferring an aqueous ink or a thermofusible ink by the ink-jet process, and PA1 4) a printing apparatus for screen process printing, letterpress printing, offset printing or stencil printing.
The present invention also relates to an image-receiving member for use with the above-mentioned image transfer method.
2. Discussion of Background
In recent years, with the spread and development of the copying and printing apparatuses, not only the originally-developed use of each apparatus, that is, to produce an image to an image-receiving medium, but also new uses have been actively studied based on the applied functions of the apparatus.
For example, there is proposed a method of transferring an image obtained on an image transfer sheet using the copying and printing apparatuses to an image-receiving member such as cloth, canvas, Japanese paper, bond paper, plastics, wood, leather, glass, earthenware or metal, and fixing the image thereto. To be more specific, the above-mentioned image transfer method can be effectively applied to the manufacturing of clothes such as T-shirts, sweat shirts, aprons and jackets, cups, trays, tiles, stained glass, panels, and reproduced pictures which are made to order, or designed to be sold on a small scale, not by mass-production. Further, such demand has greatly expanded because high quality images can be more easily printed on the image-receiving members by using a full-color dry-type electrophotographic copying apparatus.
An image transfer sheet from which the above-mentioned copied or printed image is transferred to the image-receiving member is conventionally known, for instance, as disclosed in Japanese Laid-Open Patent Application 52-82509. For instance, such an image transfer sheet comprises a support and a thermal transfer layer formed thereon, on which the image is formed using the copying or printing apparatus. When the copied or printed image formed on the above-mentioned conventional image transfer sheet is transferred to the image-receiving member, the image-bearing thermal transfer layer of the image transfer sheet is brought into contact with an image-receiving member under the application of heat and pressure thereto, thereby transferring the image to the image-receiving member. Thereafter, only the support may be released from the image-receiving member.
The above-mentioned conventional image transfer method has the drawback that the image cannot be clearly transferred to an image-receiving member of which surface smoothness is low, for example, canvas.
The reason for this will now be explained with reference to FIG. 1.
As shown in FIG. 1, the surface roughness of an image-receiving member 2 is high, and there are convex and concave portions on the surface thereof. An image transfer sheet is pressed to the image-receiving member 2 under the application of heat and pressure thereto according to the conventional image transfer method. In this case, an image-bearing thermal transfer layer 1 of the image transfer sheet is mostly filled into the concave portions on the surface of the image-receiving member 2 if the maximum height of surface roughness of the image-receiving member 2 exceeds the thickness of the thermal transfer layer 1 of the image transfer sheet. As a result, the image-bearing thermal transfer layer 1 is scarcely formed on the convex portions, so that there appear non-printed spots in the transferred image.
In the case where thermal printing is carried out using a thermofusible image transfer ink ribbon and a thermal head, of which technical field is different from that of the present invention, there is the problem that ink images cannot be sharply formed on a paper such as bond paper with a low surface smoothness. In this case, the cause of the problem is contrary to that of the conventional problem concerning to the present invention. Namely, the thermally fused ink is not transferred to the concave portions although it is transferred to the convex portions of the rough paper.
In the aforementioned field of thermal printing using the thermofusible image transfer ink ribbon, there is proposed a thermofusible image transfer ink ribbon comprising a filling-up layer which comprises an adhesive layer and a bridging transfer layer, as disclosed in Japanese Laid-Open Patent Application 7-257058, in order to improve the sharpness of the image printed on the rough paper. According to this application, before the thermofusible ink is imagewise transferred to the rough paper, the filling-up layer of the ink ribbon is thermally transferred to the surface of the rough paper so as to compensate the surface roughness of the paper. In this case, the filling-up layer transferred to the surface of paper forms an image-receiving layer with a bridging structure on the convex portions of the rough paper, as shown in FIG. 2. In FIG. 2, reference numeral 2' indicates a rough paper, and reference numeral 3 indicates a bridging transfer layer transferred from the ink ribbon.
By the above-mentioned method, the surface profile of the image-receiving member, such as the texture of bond paper is concealed by the filling-up layer, so that it is impossible to obtain sharp images without impairing the texture of the image-receiving member.
Furthermore, in the field of thermal printing using the thermal head and thermofusible image transfer ink ribbon, it is also proposed in Japanese Laid-Open Patent Application 59-95194 that a thermofusible binder be coated on the surface of an image-receiving member in advance. In this application there is the description that the adhesion of the thermally-transferred ink image to the image-receiving member is increased by previously coating on the image-receiving member a thermofusible binder with a fusion temperature lower than that of the thermofusible ink. In light of the above-mentioned description, it is apparent that the object is to improve the fixing performance of ink image thermally transferred to the surface of the image-receiving member.
Any of the previously mentioned two inventions, that relates to the thermal printing process using the thermal head and thermofusible image transfer ink ribbon, is not intended to clearly transfer the image formed on an image transfer sheet to the image-receiving member with a low surface smoothness without impairing the feeling and texture of the image-receiving member.